The prior art is replete with references pertaining to the "sol-gel" technology for the production of ceramic particles such as powders. Generally, a "sol-gel" process is one which converts a colloidal dispersion, sol, aquasol or hydrosol of a metal oxide (or precursor thereof) to a "gel". A gel is a material formed wherein one or more of the components are cross-linked either chemically or physically to such an extent as to cause a three-dimensional network to form. The formation of this network results in an increase in viscosity of the mixture and a mechanical immobilization of the liquid phase within the network. The gelling step is often followed by a drying process. Thereafter, the dried composition or xerogel is then fired to obtain a ceramic material.
In the sol-gel method for producing ceramic particles, a xerogel is often obtained. The xerogel resulting from a sol-gel process is obtained from concentrating a colloidal dispersion (i.e., a sol) to form a gel by means of solvent extraction and then drying this gel.
In conventional sol-gel processes, it is very difficult to control the quality of the final product since product quality depends largely upon process conditions (e.g., pH, concentrations, solvent extraction rates and methods, colloidal particle size, and the like). Accordingly, due to the continually increasing demand for ceramic particles having a high level of purity, the industry would greatly welcome an improved process for preparing such materials, wherein the improved process has a lower degree of process control, and a higher degree of product reproduceability and quality.